In a wideband satellite communication system, a narrow beam antenna is used to transmit information between an individual subscriber unit ground station and a satellite in orbit about the Earth. The need for a narrow beam antenna is dictated by the link budget requirements for the wideband satellite-to-ground radio frequency link. In a narrow beam satellite communication system, an excessive amount of time can be expended in executing a search pattern in order to point the beam towards a satellite whose position varies as a function of time. In a low earth orbit communication satellite system, where the motion of a satellite relative to a ground station suggests that the satellite will be visible for only a few minutes, it is especially advantageous to direct a narrow beam antenna to the precise direction of a satellite in a very short period of time. Additionally, as the satellite moves in its orbit, the ground station narrow beam antenna must be constantly redirected to the position of the satellite in order to ensure uninterrupted communication.
In a currently proposed communication satellite system architecture, the ground station narrow beam antenna is directed toward the satellite based on predictions of the satellite position. Thus, the ground station must be apprised of the satellite position in advance of the satellite becoming visible in order to acquire and remain in contact with the satellite. In a wideband satellite communication system comprising a constellation of non-geostationary satellites, the ephemeris of the satellites can be extensive. Additionally, changes in the satellite velocity and direction vector caused by atmospheric drag, solar wind, or other phenomena, cause the ephemeris to require periodic updating. Even with such updating, the ground station may still require substantial time to search for the satellite using a narrow antenna beam.
Therefore, what is needed, are a method and system for antenna beam steering to the satellite through the broadcast of the satellite position. Such a system would greatly reduce the search time for a narrow beam to acquire the communication satellite.